Featured Artist: Ivan Larinin, Montreal, Canada

The shot was complex, involving a fast-driving character. Speed presents a particular challenge in VFX, as it necessitates additional substeps between frames and meticulous attention to motion blur. If I had performed a particle simulation for a moving character, the difference between one frame and the next would have been too substantial to achieve reasonable interpolation. This would require significantly more substeps, leading to a loss of control over the simulation, increased iteration time, and extended rendering times on a farm.

To address the issue of ash dissipation and ensure accurate simulation, we placed the character in the center of a grid, simulated the ash from this central position, and then transferred the velocity from the original character's movement. Afterward, we moved the character back to its original position. Additionally, I utilized three different fluid simulations to advect the particles based on fluid forces. One of these simulations was specifically designed to handle the swirling effect behind the character, adding a layer of realism to the scene.

To refine the effect, I used a Distance Along Geometry technique to calculate an expanding mask around the character. This was done to match the timing desired by the director, with the addition of noise to introduce some randomness and liveliness to the movement. Several layers were then merged, and various render masks were computed using attributes such as age, life, and speed. This approach added transparency and enhanced the overall randomness of the look, contributing to a more dynamic and visually engaging final result.